IOP Conference Series: Materials Science and Engineering PAPER • OPEN ACCESS Kinetics of Mixed Amino Acid and Ionic Liquid on CO2 Hydrate Formation To cite this article: Cornelius B. Bavoh et al 2019 IOP Conf. Ser.: Mater. Sci. Eng. 495 012073 View the article online for updates and enhancements. This content was downloaded from IP address 181.215.220.240 on 12/06/2019 at 14:38 CUTSE IOP Publishing IOP Conf. Series: Materials Science and Engineering 495 (2019) 012073 doi:10.1088/1757-899X/495/1/012073 Kinetics of Mixed Amino Acid and Ionic Liquid on CO2 Hydrate Formation Cornelius B. Bavoh1,2, Bhajan Lal1,2,*, Joel Ben-Awuah3,*, Muhammad Saad Khan1,2, Grace Ofori-Sarpong4, 1 Chemical Engineering Department, Universiti Teknologi PETRONAS, Bandar Seri Iskandar, 32610, Perak, Malaysia. 2 CO2 Research Centre (CO2RES), Bandar Seri Iskandar, 32610, Perak, Malaysia. 3 Department of Applied Geology, Curtin University, Malaysia, CDT 250, Miri 98009, Sarawak, Malaysia. 4 Petroleum Engineering Department, University of Mines and Technology, Tarkwa, P.O Box 237, Ghana. *jbenawuah@curtin.edu.my ; bhajan.lal@utp.edu.my Abstract. The formation of gas hydrate in oil and gas and carbon dioxide sequestration processing pipelines is unwanted and must be prevented for easy and safety processes. However, conventional kinetic hydrate inhibitors are less effective and thus, new inhibitors are required to effectively manage hydrate formation in the industry. Recently, ionic liquids and amino acids have been introduced as potential kinetic gas hydrate inhibitors (KHIs). But the quest for highly effective amino acids and ionic liquids hydrate inhibitors is still on going with no desired inhibition impact reported so far. Hence, a blend of these two classes of novel kinetic hydrate inhibitor may possibly perform better. Herein, the combined kinetic gas hydrate inhibition effect of some best performed amino acid (glycine) and ionic liquid (1-Ethyl-3-methy-limidazolium chloride) is reported on CO2 hydrate formation. The study was conducted in a sapphire hydrate cell using the constant cooling isochoric mode at 50/50 wt.% concentration of glycine and 1Ethyl-3-methy-limidazolium chloride at a total concentration of 1 wt.%. All experiments were performed at 3.5 MPa and 274.15 K. The results showed that, all studied systems (pure glycine and 1-Ethyl-3-methy-limidazolium chloride and their mixture) inhibited CO 2 hydrate formation by increasing its induction time and reducing the total moles of CO2 converted into hydrate. The inhibition impact of glycine was less than 1-Ethyl-3-methy-limidazolium chloride, but surprisingly their combined effect was less than 1-Ethyl-3-methy-limidazolium chloride but higher than glycine base on induction time and CO2 uptake evaluation. Keywords: Carbon dioxide; Gas hydrate; Kinetics; Glycine; 1-Ethyl-3-methy-limidazolium chloride 1. Introduction The formation of gas hydrate in oil and gas pipelines is undesired and must be prevented. During oil and gas production, the presence of reservoir water, hydrocarbons, low temperature and high-pressure condition assures serious gas hydrate threat which must be well predicted and avoided. Gas hydrates are ice-like compounds which are formed by the trapping of gas molecules in hydrogen bonded water cages at low temperatures and high pressures. [1–3]. There are three types of gas hydrate structures; structure Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Published under licence by IOP Publishing Ltd 1 CUTSE IOP Publishing IOP Conf. Series: Materials Science and Engineering 495 (2019) 012073 doi:10.1088/1757-899X/495/1/012073 I, structure II and structure H. However, their structures are dependent on the type, size, and guest-tocage size ratio of the gas molecule [4,5]. The formation of gas hydrates in oil and gas transmission pipelines may cause blockages due to its crystal solid nonflowing structures [6]. The formation of hydrate may also result in several safety problems, which in severe cased can lead to loss of lives. Hence, the formation of hydrates in hydrocarbon flow assurance are seriously unwanted. The oil and gas industries spend about 70% of their OPEX on the removal of hydrate plugs. Therefore, to ensure hydrate free operations, much attention is focused on the development of hydrate preventive methods form both academia and industry alike. There are four methods of preventing hydrate formation and plugs; water removal, depressurization, thermal heating, and injection of chemical inhibitors. The best and practicable method is the injection of chemical inhibitors to disrupt the chemical potential of the water molecules either kinetically or thermodynamically. Thermodynamic inhibitors such as methanol, and glycols are used to reduce the risk of hydrate plugging in pipelines by shifting the hydrate phase equilibria to low temperature and high pressure regions [7]. However, conventional THIs have several problems. In particular, the toxic nature of these chemicals causes serious environmental pollution in ecological systems and critical damage to the polymer used to seal pipelines [8]. Therefore, low-dosage hydrate inhibitors (LDHIs) were introduced to replace the thermodynamic inhibitors. These class of inhibitors are used to reduce the nucleation time and at the same time reduced the hydrate formation rate and gas uptake. Generally, LDHIs are polymers such as PVP and PVCap. However, the capabilities of LDHIs to prevent hydrate formation are associated with uncertainties arising from the stochastic nature of hydrate nucleation and other kinetic factors [9]. In addition, the current LDHIs are not effective at lower subcooling conditions. Therefore, the development/discovery of new LDHIs is necessary for effective hydrate plug prevention, especially in deep sea operations. Currently, there is a continuous search for novel LDHIs that can solve the problems that limits present techniques, especially kinetic gas hydrate inhibitors (KHIs). In searching for new KHIs inhibitors, ionic liquids (ILs) and amino acids are recently reported as novel KHIs for gas hydrate mitigations [3,10,11]. The kinetic hydrate inhibition impact of ionic liquids is attributed to their hydrogen bonding potentials and hydrophobic nature arising from the anions and cation of ionic liquids. [12–15]. On the other hand, amino acids are believed to perturbed water molecules via hydrogen bonding interaction with water molecules, thereby, delaying the hydrate nucleation time and growth kinetics [11,16–18]. These recent discoveries have led to much research [19–21] in discovering the best ILs or amino acids that can perform better than the conventional KHIs. Most especially imidazolium base ILs and natural amino acids have received much attention and studies in these regards. Literature shows that 1-Ethyl-3-methy-limidazolium chloride and Glycine are one of the best gas hydrate inhibitors among the imidazolium ionic liquid family and naturally occurring amino acids. We previously reported that PVP slightly inhibits CO2 hydrate than 1-Ethyl-3-methy-limidazolium chloride at 1 wt.% [19,22,23]. Sa et al[24] also presented that the kinetic inhibition strength of glycine and PVP are in the same range on the bases of subcooling and gas uptake [17,25]. Nonetheless, this inhibition performance is relatively weak as against the conventional KHIs, therefore a synergist study of the some of the best performed ILs and amino acids inhibitors is encouraging to develop effective KHIs. In addition, the scarcity of ILs + amino acids synergistic study in open literature is a motivating factor for conducting this study. In this study, the synergic kinetic effect of 1-Ethyl-3-methy-limidazolium chloride (ILs) + glycine (amino acid) on carbon dioxide hydrate formation is studied in an isochoric mode at a total concentration of 1 wt.% synergy (0.5 wt.% 1-Ethyl3-methy-limidazolium chloride + 0.5 wt.% glycine). 2. Methodology 2.1. Materials Fig. 1 shows the chemical structure of 1-Ethyl-3-methy-limidazolium chloride and glycine. The 1-Ethyl3-methy-limidazolium chloride (EMIM-Cl) (purity 98%) and Glycine (purity 99.7%) were provided by Merck Malaysia and were used without further purification. Carbon dioxide (purity 99.995%) was supplied by Gas Walker Sdn Bhd, Malaysia. All samples were prepared with deionized water. The 2 CUTSE IOP Publishing IOP Conf. Series: Materials Science and Engineering 495 (2019) 012073 doi:10.1088/1757-899X/495/1/012073 chemicals were tested at 1 wt.% (50:50 % synergy of 1-Ethyl-3-methy-limidazolium chloride and glycine). 1-Ethyl-3-methy-limidazolium chloride Glycine Fig. 1. Chemical structure of 1-Ethyl-3-methy-limidazolium chloride and glycine 2.2. Experimental apparatus and Kinetic measurement procedure The experimental apparatus and methods used in this study are explained into details elsewhere [19,22,26–29]. To effectively evaluate the CO2 hydrate formation kinetics in the presence of mixed EMIM-Cl and glycine, an Isochoric constant cooling method was adopted. A sapphire hydrate cell with volume of 29 ml was employed. The system can operate at a maximum pressure and temperature of 20 MPa and 338.15 K, respectively. Prior to all experiments, the cell is washed and dried thoroughly to remove all contaminants. The system temperature is then set to about 2-3 K above the desired hydrate equilibrium temperature of the testing experimental pressure (in this case 3.6 MPa). The desired testing solution (0.5 wt.% 1-Ethyl-3-methy-limidazolium chloride + 0.5 wt.% glycine) is pumped into the reactor via a hand pump. Pure carbon dioxide is then pressurized into the cell and allowed to stabilize at 3.6 MPa with the stirrer on. After one hour, when the system is stabilized, the system temperature is reduced constantly to 274.15 K at 4 K/h for hydrate to form. The formation of hydrate in the reactor is noticed by observing a sharp system pressure drop and visually through the reactor and via the pressure time plot as shown in Fig 2. The experiment is considered done when the system pressure remains constant for about 3 – 5 hours after hydrate formation. A data acquisition system is attached to the system to continuously record the pressure and temperatures changes in the reactor with an accuracy of ± 0.1 K and ± 0.01 MPa, respectively. Fig. 2. A typical Pressure vs time plot for CO2 hydrate formation. The induction time, ti describes the ability of a kinetic hydrate inhibitor to delay hydrate formation nucleation. It is defined in practice as the time taken for the formation of a detectable volume of hydrate phase or the time taken for an inhibitor to fail [3]. High induction time indicates greater inhibition. The induction time is a very important parameter for hydrate prevention during drilling of hydrate sediments. It characterizes the retention time the drilling can prevent hydrate agglomeration and growth in the wellbore. The induction time is calculated from the pressure – time plotted as illustrated in Fig. 2 as; 3 CUTSE IOP Publishing IOP Conf. Series: Materials Science and Engineering 495 (2019) 012073 doi:10.1088/1757-899X/495/1/012073 ti  ts  th (1) where ts is time taken for the system temperature and pressure to stabilize at experimental pressure, and th is the time when detectable hydrate is noticed and grow rapidly, indicated by a sharp pressure drop due to gas consumption into hydrate. To calculate the amount of gas consumed into hydrate, the real gas equation is employed to determine the difference between the number of, nH of moles of gas at time zero and time t during hydrate formation process as given in equation 2. ∆𝑛𝐻 = [ 𝑃𝑉 𝑃𝑉 ] −[ ] 𝑧𝑅𝑇 𝑡 𝑧𝑅𝑇 0 (2) where, P, V, T and R are system pressure, gas phase volume, temperature and universal gas constant respectively. 3. Results and Discussions In this study, induction time and total gas uptake were used to evaluate the kinetic inhibition impact of mixed EMIM-Cl and glycine. Though adopting induction time to determine the KHI performance may sometimes lead to wrong judgment, since hydrate formation is a probabilistic process [30]. However, induction time is still the main important KHI indicators, because it describes the retention time of the gas stream to prevent hydrate formation, especially at high pressure and/or subcooling conditions [31]. In this work, the experiments were conducted at high pressure (3.6 MPa), thus using induction time will give a clear representation of hydrate prevention impact in the presence of the tested inhibitors. Table 1 presents the measured induction time of carbon dioxide hydrate in the presence of all studied systems in this work. Its observed that, the presence of both pure and mixed EMIM-Cl and glycine significantly delayed the CO2 hydrate nucleation time. EMIM-Cl exhibited the highest induction time inhibition impact of about 114% delay in the hydrate formation nucleation. Glycine delayed the CO 2 hydrate induction time of about 42% against 64% for mixed 0.5wt%. EMIM-Cl + 0.5wt%. glycine. This indicates that, instead of expecting a high inhibition strength when both inhibitors are combined, the presence of glycine reduces the inhibition strength of ionic liquids (EMIM-Cl). Contrary, the presence of EMIM-Cl increases the kinetic inhibition impact of amino acids (glycine). Table 1: The Measured induction time of CO2 hydrate in the presence of EMIM-Cl + PVP synergic system Systems Induction time (min) Pure water Glycine EMIM-Cl 0.5 wt%. EMIM-Cl + 0.5 wt%. Glycine 4 14.46 20.67 30.17 23.83 CUTSE IOP Publishing IOP Conf. Series: Materials Science and Engineering 495 (2019) 012073 doi:10.1088/1757-899X/495/1/012073 0.007 CO2 uptake (mol) 0.00602 0.006 0.005 0.00448 0.00397 0.004 0.003 0.00173 0.002 0.001 0 Pure water Glycine EMIM-Cl 0.5 wt% EMIM-Cl + 0.5 wt% Glycine Fig. 3. CO2 uptake during hydrate formation in all studied systems at 1 wt.%. Interestingly, a similar trend of induction time inhibition is observed in Fig. 3 for the total CO 2 gas uptake. A CO2 uptake inhibition of about 128% was exhibited by pure EMIM-Cl, followed by 34% for mixed 0.5wt%. EMIM-Cl + 0.5wt%. pure glycine, and 25.5% for glycine. It can be deduced that, in synergy of EMIM-Cl and glycine positively favors glycine but negatively affects EMIM-Cl. In our previous studies on the synergic effect of EMIM-Cl and PVP a similar poor inhibition impact was observed compared with pure PVP [20,32]. These was found to be due to interactions between EMIM-Cl and PVP molecules which reduces the absorption ability of PVP and causes more CO 2 to dissolve into liquid phase, hence, enhancing hydrate formation. Herein, the presence of glycine and EMIM-Cl have similar interaction behavior which probably causes a steric orientation of the hydrogen bonded water structure to align in a way which promotes hydrate formation. 4. Conclusion In this work, the induction time and total gas uptake for pure and mixed EMIM-Cl + glycine on CO2 hydrate formation have been evaluated in an isochoric constant cooling mode at 1wt.%. The results show that, the synergic effect of EMIM-Cl + glycine enhances the KHI performance of amino acids (glycine) but significantly reduces that of ionic liquids (EMIM-Cl). It is therefore recommended that, further studies on different hydrate formers at different operational conditions is needed for the development of effective KHIs and to better understand the kinetic inhibition mechanism of gas hydrates in the presence of mix inhibitors. 5. Acknowledgments The authors would like to acknowledge the Universiti Teknologi PETRONAS for their financial support. 6. References [1] E. D. Sloan and C. A. Koh, "Clathrate hydrates of natural gases", vol 87 (Baca Raton: CRC Press), 2007. [2] E. Broni-Bediako, R. Amorin and C. B. Bavoh, "Gas Hydrate Formation Phase Boundary Behaviour of Synthetic Natural Gas System of the Keta Basin of Ghana" Open Pet. Eng. J., 10, 64–72, 2017. [3] C. B. Bavoh, M. S. Khan, B. Lal, N. I. Bt Abdul Ghaniri and K. M. Sabil, "New methane hydrate phase boundary data in the presence of aqueous amino acids" Fluid Phase Equilib. 478, 129–33, 2018. [4] G. A. Jeffery, "Pentagonal Dedecahedral Water Structure in Crystalline Hydrates" Mat. Res. Bull, 7, 1259–70,1972. [5] J. A. Ripmeester, J. S. Tse, C. I. Ratcliffe and B. M. Powell, "A new clathrate hydrate structure" 5 CUTSE IOP Publishing IOP Conf. Series: Materials Science and Engineering 495 (2019) 012073 doi:10.1088/1757-899X/495/1/012073 [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] [16] [17] [18] [19] [20] [21] [22] [23] [24] [25] Nature 325, 135–6, 1987 E. G. Hammerschmidt, "Formation of gas hydrates in natural gas transmission lines" Ind. Eng. Chem., 26, 851–5, 1934. C. A. Koh, "Towards a fundamental understanding of natural gas hydrates" Chem. Soc. Rev., 31, 157–67, 2002. C. A. Koh, E. D. Sloan, A. K. Sum and D. T. Wu, "Fundamentals and Applications of Gas Hydrates Annu. Rev. Chem. Biomol. Eng., 2, 237–57, 2011. M. A. Kelland, "History of the Development of Low Dosage Hydrate Inhibitors" Energy Fuels 20, 825–47, 2006. C. Xiao and H. Adidharma, "Dual function inhibitors for methane hydrate" Chem. Eng. Sci., 64, 1522–7, 2009. J. H. Sa, B. R. Lee, D. H. Park, K. Han, H. D. Chun and K. H. Lee, "Amino acids as natural inhibitors for hydrate formation in CO2 sequestration" Environ. Sci. Technol., 45, 5885–91, 2011. C. B. Bavoh, B. Lal, O. Nashed, M. S. Khan, K. K. Lau and M. A. Bustam, "COSMO-RS: An ionic liquid prescreening tool for gas hydrate mitigation" Chinese J. Chem. Eng., 24(11): 16191624, 2016. M. Tariq, D. Rooney, E. Othman, S. Aparicio, M. Atilhan and M. Khraisheh, "Gas Hydrate Inhibition : A Review of the Role of Ionic Liquids" Ind. Eng. Chem. Res., 53, 17855–68, 2014. M. S. Khan, C. S. Liew, K. A. Kurnia, B. Cornelius and B. Lal, "Application of COSMO-RS in Investigating Ionic Liquid as Thermodynamic Hydrate Inhibitor for Methane Hydrate" Procedia Eng., 148, 862–9, 2016. M. S. Khan, B. Partoon, C. B. Bavoh, B. Lal and N. B. Mellon, "Influence of tetramethylammonium hydroxide on methane and carbon dioxide gas hydrate phase equilibrium conditions" Fluid Phase Equilib., 440, 1–8, 2017. J. H. Sa, G. H. Kwak, K. Han, D. Ahn, S. J Cho, J. D. Lee and K. H. Lee, "Inhibition of methane and natural gas hydrate formation by altering the structure of water with amino acids" Sci. Rep. 6, 31582, 2016. C. B. Bavoh, B. Partoon, B. Lal and L. K. Keong, "Methane hydrate-liquid-vapour-equilibrium phase condition measurements in the presence of natural amino acids" J. Nat. Gas Sci. Eng., 37, 425–34, 2016. C. B, Bavoh, B. Partoon, B. Lal, G. Gonfa, S. Foo Khor and A. M. Sharif, "Inhibition Effect of Amino Acids on Carbon Dioxide Hydrate" Chem. Eng. Sci., 171, 331–9, 2017. C. B. Bavoh, B. Lal, L. K. Keong, M. binti Jasamai and M. binti Idress, "Synergic Kinetic Inhibition Effect of EMIM-Cl + PVP on CO2 Hydrate Formation" Procedia Eng. 148 1232–8, 2016. C. B. Bavoh, B. Partoon, L. K. Keong, B. Lal and C. D. Wilfred, "Eeffect of 1-ethyl-3methylimidazolium chloride and polyvinylpyrrolidone on kineticss of carbon dioxide hydrates" Int. J. Appl. Chem., 12, 6–11, 2016 M. S. Khan, C. B. Bavoh, B. Partoon, B. Lal, M. A. Bustam and A. M. Shariff, "Thermodynamic effect of ammonium based ionic liquids on CO2 hydrates phase boundary J. Mol. Liq., 238, 533539, 2017. C. B. Bavoh, B. Partoon, L. K. Keong, B. Lal and C. D. Wilfred, "Effect of 1-ethyl-3methylimidazolium chloride and polyvinylpyrrolidone on kinetics of carbon dioxide hydrates" Int. J. Appl. Chem., 12, 6–11, 2016. C. B. Bavoh, B. Lal, M. S. Khan, H. Osei and M. Ayuob, "Combined Inhibition Effect of 1Ethyl-3-methy-limidazolium Chloride + Glycine on Methane Hydrate" J. Phys. Conf. Ser., 1123, 012060, 2018. J. H. Sa, G. H. Kwak, B. R. Lee, D. H. Park, K. Han and K. H. Lee, "Hydrophobic amino acids as a new class of kinetic inhibitors for gas hydrate formation" Sci. Rep., 3, 2428, 2013. Z. Long, X. Zhou, X. Shen, D. Li and D. Liang, "Phase Equilibria and Dissociation Enthalpies of Methane Hydrate in Imidazolium Ionic Liquid Aqueous Solutions" Ind. Eng. Chem. Res., 54, 11701–8, 2015. 6 CUTSE IOP Publishing IOP Conf. Series: Materials Science and Engineering 495 (2019) 012073 doi:10.1088/1757-899X/495/1/012073 [26] [27] [28] [29] [30] [31] [32] C. B. Bavoh, B. Partoon, B. Lal and L. Kok Keong, "Methane hydrate-liquid-vapour-equilibrium phase condition measurements in the presence of natural amino acids" J. Nat. Gas Sci. Eng. 37, 425-434, 2017. C. B. Bavoh, B. Partoon, B. Lal, G. Gonfa, S. Foo Khor and A. M. Sharif, "Inhibition effect of amino acids on carbon dioxide hydrate" Chem. Eng. Sci. 171, 331-339, 2017. C. B. Bavoh, O. Nashed, M. S. Khan, B. Partoon, B. Lal and A. M. Sharif, "The impact of amino acids on methane hydrate phase boundary and formation kinetics" J. Chem. Thermodyn., 117 48–53, 2018. C. B. Bavoh, O. Nashed, M. S. Khan, B. Partoon, B. Lal and A. M. Sharif, "The impact of amino acids on methane hydrate phase boundary and formation kinetics" J. Chem. Thermodyn., 117 48–53, 2018. F. Farhang, A. V. Nguyen and M. A. Hampton, "In fluence of Sodium Halides on the Kinetics of CO2 Hydrate Formation" Energy and Fuels, 28. 1220–9, 2014. B. Partoon and J. Javanmardi, "Effect of mixed thermodynamic and kinetic hydrate promoters on methane hydrate phase boundary and formation kinetics" J. Chem. Eng. Data, 58, 501–9, 2013. C. B. Bavoh, B. Lal, L. K. Keong, M. B. Jasamai and M. B. Idress, "Synergic Kinetic Inhibition Effect of EMIM-Cl + PVP on CO2 Hydrate Formation" Procedia Engineering, vol 148, 12381238. 7